Middle ring - is this broken?
Discussion
Trying to get to the bottom of the problem with my chain jumping, I'm thinking this is the culprit:
I remember from my youth that there used to be some non uniform shaped chainrings but this seems extreme to me? I'm guessing the solution is new chain & chainring - rest of the drivetrains looks & operates fine. Does the ring look knackered to you? (fnarr fnarr!)
PS Is there anything particularly special about Shimano IG chains? Any recommended upgrades/replacements other than same again?
I remember from my youth that there used to be some non uniform shaped chainrings but this seems extreme to me? I'm guessing the solution is new chain & chainring - rest of the drivetrains looks & operates fine. Does the ring look knackered to you? (fnarr fnarr!)
PS Is there anything particularly special about Shimano IG chains? Any recommended upgrades/replacements other than same again?
It doesn't look too bad really, it's worn but there's no real hooking where the front side of a tooth wears away to create a point. If and when you get a new chain get a KMC, they're the best. Thing is if you change the ring and chain you should really change the cassette too, and all of a sudden it's got expensive!
What is the problem anyway, other than the need for a clean?
What is the problem anyway, other than the need for a clean?
Thanks for replies! Main problem is the chain jumping when I'm pedaling hard - only seems to happen on the middle ring though? Pretty sure the drivetrain is as it should be as I've had this bike for about 8 years now(!) and its only just started to become a problem. Perhaps just giving the thing a damn good clean, regrease & adjust the gears is all it needs before I start down the road of throwing new (and potentially expensive!) components at it.....
smack said:
It is rather worn, and you have lost teeth, so I would not be surprised it is jumping.
And yes, it is old 8 speed XT.
I think those "lost teeth" are just smaller ones to aid shifting...?And yes, it is old 8 speed XT.
IMO it doesn't look too worn - I've used worse - but it's difficult to tell with the chain: it could be worn and you just don't know visually. Best solution is to buy a chain stretch measuring tool for less than a tenner. They're great at checking if your chain has stretched, which could be the cause of the jumping.
I'd hazard a guess, that what you are experiencing is chainsuck. If any of those teeth are damaged enough to not release the chain, then it's going to be a problem.
At minimum you will need a new middle ring, probably a new chain, and if you go that far then may as well get a new casssette.
Try ebay or chain reaction for cheap deals on older stock.
You will also need a few tools to fit all that.(See Tool Kit thread)
At minimum you will need a new middle ring, probably a new chain, and if you go that far then may as well get a new casssette.
Try ebay or chain reaction for cheap deals on older stock.
You will also need a few tools to fit all that.(See Tool Kit thread)
a11y_m said:
I think those "lost teeth" are just smaller ones to aid shifting...?
No, the tips have broken off from wear/use. Some makes will have different profiles of the teeth, but those, and Shimano years after that didn't. I used to sell/fix that era of kit years ago.a11y_m said:
IMO it doesn't look too worn - I've used worse - but it's difficult to tell with the chain: it could be worn and you just don't know visually. Best solution is to buy a chain stretch measuring tool for less than a tenner. They're great at checking if your chain has stretched, which could be the cause of the jumping.
Yes, I have used worse, but I would run part worn cassettes/chains on my bikes (with badly worn chainrings) rather than new to keep it going, usually over winter. And wait until spring to put the new drivetrain on rather than half trash it in the mud and grit.If you put a new cassette/chain on that, the chain will have to stretch to 'mate' to worn chainrings. It won't shift right, and suffer from chain suck until it does, quickly wearing out your new chain and cassette. Doing that way is a false economy.
itsnotarace said:
trackdemon said:
Main problem is the chain jumping when I'm pedaling hard
More than likely a stiff link on that rusty chaintrackdemon said:
Thanks for replies! Main problem is the chain jumping when I'm pedaling hard - only seems to happen on the middle ring though? Pretty sure the drivetrain is as it should be as I've had this bike for about 8 years now(!) and its only just started to become a problem. Perhaps just giving the thing a damn good clean, regrease & adjust the gears is all it needs before I start down the road of throwing new (and potentially expensive!) components at it.....
I had the same symptoms on a second hand bike except it was on the middle and largest chain ring. I changed the chain, then cassette, then freewheel but the problem remained the same. Bought two new Shimano chainrings from Ebay for all of about £7 for the pair and it was cured. My ring piece was also less worn than yours looks.Best of luck cleaning it but I'd try and grab a cheap replacement if I were you. It should only require one Allen key to change it, obviously to change the chain/cassette will need more specialist tools.
-- Just noticed you described it as 'jumping', whereas mine was slipping when under extreme force, not sure if that's what you're suffering.
Edited by TheInternet on Thursday 8th December 20:18
smack said:
a11y_m said:
I think those "lost teeth" are just smaller ones to aid shifting...?
No, the tips have broken off from wear/use. Some makes will have different profiles of the teeth, but those, and Shimano years after that didn't. I used to sell/fix that era of kit years ago.The flat teeth visible in the OP's photo would be in the same place if the ring had been fitted correctly!
OP - you'll find that you get better shifts if you rotate the middle ring so that the tab on the inside is behind the crank
Check this on the inner one too.Could....Not.... Re...sist...
TheInternet said:
My ring piece was also less worn than yours looks.
Best of luck cleaning it but I'd try and grab a cheap replacement if I were you.
-- Just noticed you described it as 'jumping', whereas mine was slipping when under extreme force, not sure if that's what you're suffering.
Best of luck cleaning it but I'd try and grab a cheap replacement if I were you.
-- Just noticed you described it as 'jumping', whereas mine was slipping when under extreme force, not sure if that's what you're suffering.
Edited by TheInternet on Thursday 8th December 20:18
TheInternet said:
My ring piece was also less worn than yours looks.
TheInternet said:
-- Just noticed you described it as 'jumping', whereas mine was slipping when under extreme force, not sure if that's what you're suffering.
Different wording, but meaning exactly the same I think....magpie215 said:
looks exactly like mine the most worn teeth are directly in line with where the crank arms will transmit max torque.
I just rotated the chainring to freshen up the teeth at the max torque position.
Hmmm, interesting. I don't think my sitting pedalling technique has particularly large peaks and troughs, as I use SPD's and was trained to power the whole rotation - but I don't suppose there's any harm in giving it a try!I just rotated the chainring to freshen up the teeth at the max torque position.
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